ELECTRONIC-STRUCTURE IN ICOSAHEDRAL ALCULI QUASI-CRYSTALS AND APPROXIMANT CRYSTALS

The electronic structure has been calculated for large approximant cry stals (up to 51 752 atoms in the periodically repeated cell) to icosah edral AlCuLi quasicrystals. The results show that a deep structure-ind uced pseudogap at the Fermi energy is a generic property of the quasic rystal and its crystalline approximants. The physical mechanism for th e formation of the gap is discussed on the basis of a quasiperiodic ge neralization of the nearly-free-electron model.